Transmission unit for axles for vehicles with electric drive

ABSTRACT

A transmission unit for axles for vehicles with electric drive comprises a drive gear, a driven gear, and an intermediate idler gear, meshing with the drive gear and with the driven gear. The unit is housed in half-shells. The intermediate idler gear is mounted on a pin the central portion of which is eccentric by a predetermined amount with respect to the axis extending through the end portions of the pin, which are engaged in the half-shells. Angularly spaced radial holes formed in one end portion of the pin are selectively engageable by a resilient split pin which extends through a radial hole formed in one of the half-shells.

[0001] The present invention relates to a transmission unit for axles for vehicles with electric drive.

[0002] Vehicles with electric drive are used in various applications, for example, for moving luggage in railway stations and/or airport facilities, for transporting people on golf courses, etc.

[0003] The transmission unit for such a vehicle is normally composed of a train of gears in which a drive gear takes the drive from the shaft of an electric motor and transmits it to the driven gear which in turn transmits the drive to the wheel axle of the vehicle.

[0004] In some cases, an intermediate idler gear is interposed between the drive gear and the driven gear.

[0005] The unit is housed in a gear housing.

[0006] Since each of the possible uses of above-mentioned electric-drive vehicles may require a different transmission ratio, it is normally necessary to provide different drive, driven and idler gears for each type of use, possibly also with a different transmission housing.

[0007] The object of the present invention is to provide a transmission unit for axles for vehicles with electric drive which overcomes the above-mentioned problems and which is of simple construction and low cost.

[0008] The present invention achieves the above-mentioned object by means of a transmission unit for axles for vehicles with electric drive having the specific characteristics recited in the appended claims.

[0009] The invention will now be described with reference to the appended drawings, provided purely by way of non-limiting example, in which:

[0010]FIG. 1 shows the transmission unit of the present invention, in section,

[0011]FIGS. 2, 3 and 4 are side views of the transmission unit of the present invention,

[0012]FIG. 5 shows a detail of FIG. 4, on an enlarged scale, and

[0013]FIG. 6 shows, on an enlarged scale, a detail of a second embodiment of the transmission unit of the present invention.

[0014] With reference to FIG. 1, a transmission unit, generally indicated 2, comprises a drive gear 4 which takes the drive from the shaft of an electric motor (not shown) by means of a splined coupling member 6.

[0015] The drive gear 4 meshes with an intermediate idler gear 8 which in turn meshes with a driven gear 10, keyed to a bevel pinion 14 by means of a splined coupling 12.

[0016] The transmission unit 2 is supported in a housing composed of two half-shells 20 and 22.

[0017] The idler gear 8 is mounted, by means of bearings 16, on a central portion 18 of a pin 15, which is eccentric by a predetermined amount X with respect to the common rotation axis A-A of the two end portions 17, 19 of said pin, which are engaged in the half-shells 20 and 22.

[0018] A radial through-hole 24 is formed in the half-shell 20.

[0019] Radial holes 26, 28, 30, 32, formed in one end portion 17 of the pin 15 (FIGS. 4 and 5) are spaced apart angularly for the reasons which will be explained below, and can be engaged by a resilient pin 34 introduced into the radial hole 24.

[0020] To change the transmission ratio, it suffices to replace the drive gear 4 and the driven gear 10 with others having the desired transmission ratio and to displace the axis of rotation of the idler gear 8 to a position such that the drive and driven gears can be engaged.

[0021] For this purpose, the axis of the central eccentric portion 18 of the pin 15 is displaceable by rotating the pin about the common rotation axis A-A of the end portions 17, 19 thereof until the desired position is reached, that is, until one of the holes 26, 28, 30 or 32 is placed aligned with the radial hole 24, and then inserting the pin 34, thus fixing the axis of rotation of the idler gear 8 in the desired position.

[0022] In a second embodiment of the transmission unit according to the invention, shown in FIG. 6, angularly spaced radial holes 100, 101, 102 103 are formed in the half-shell 20 and a radial hole 110 is formed in the end portion 17 of the pin.

[0023] In this embodiment, in order to vary the transmission ratio, it is necessary to rotate the axis of the eccentric central portion 18 of the pin until the desired position is reached, thus placing the hole 110 aligned with one of the radial through-holes 100, 101, 102, 103, and then to insert the pin 34 through the aligned holes thus fixing the axis of the idler gear 8 in the desired position.

[0024] In the embodiment shown in FIG. 5, there are four possible different transmission ratios but, naturally, if the number of holes in one end of the pin is increased, the number of transmission ratios which can be achieved is consequently increased.

[0025] The same result is achieved in the embodiment of FIG. 6 by increasing the number of through-holes formed in the half-shell 20.

[0026] The advantages of a transmission unit according to the invention are clear from the foregoing.

[0027] The transmission ratios can be varied whilst the intermediate idler gear remains unchanged, as shown by the comparison of FIGS. 2 and 3, with clear managing and cost benefits, since the housings which contain the gear train do not need to be changed, with further clear management and cost benefits and, in order to change the transmission ratios, instead of replacing all three gears as in the prior art, it suffices to replace the drive gear (on the electric motor shaft) and the driven gear mounted on the shaft of the bevel pinion.

[0028] Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely without thereby departing from the scope of the present invention. 

What is claimed is:
 1. A transmission unit for axles for vehicles with electric drive, comprising a drive gear, a driven gear, and an intermediate idler gear meshing with the drive gear and with the driven gear, the gears being housed in half-shells, the intermediate idler gear being mounted rotatable on an intermediate or central portion of a pin having two end portions rotatably supported in said half-shells about a common axis, the central portion of the pin being eccentric by a predetermined amount with respect to said common axis; means being provided for locking the pin in different angular positions about said common axis, with respect to said half-shells.
 2. A transmission unit for axles according to claim 1 , wherein said locking means comprise a plurality of angularly spaced radial holes formed in one end portion of the pin, and a locking member extending through a radial hole formed in one half-shell and one of said radial holes of the pin.
 3. A transmission unit for axles according to claim 1 , wherein said locking means comprise a plurality of angularly spaced radial holes formed in one of the half-shells, and a locking member which extends through one of the said radial holes and through a radial hole formed in one end portion of the pin.
 4. A transmission unit according to claim 2 or 3 , wherein the locking member is constituted by a resilient split pin. 